1. Field of the Invention
The present invention relates to a method of and an apparatus for reproducing texture, and more particularly to a texture reproducing method and apparatus for presenting a virtual texture of a product, being developed, to consumers in order to allow the consumers to experience the texture of the product through their visual and tactile senses so that opinions of consumers on the product are positively reflected on developments of products.
2. Description of the Prior Art
Generally, where dress of a new fashion is developed, it is designed and made by only the experience and concepts of designers. The success of this product is determined by the degree of interests of consumers thereon exhibited after the product is put on the market.
If opinions of consumers of products being developed are reflected on those products, it is then possible to develop products having a better chance of market success. It is also possible to reduce the labor, time and costs required in the development of products.
In order to reflect opinions of consumers on products being developed, a method has been proposed in which once the design of clothing is determined by designers, samples of the clothing are made using various kinds of fabric. These samples are shown to consumers so as to obtain opinions of the consumers.
However, this method is impractical because there are a variety of clothes such as winter and summer clothes for gentlemen, winter and summer clothes for women, and clothes for traditional dress. In other words, it is practically impossible to prepare samples of such various clothes for a newly designed product.
In order to solve such a problem, a number of research efforts have been made to reproduce virtual touch. Before making a description of such research efforts, definition of the term "touch" will be made.
Generally, the term "touch" is defined as the term "tactile sensing" and the term "texture". The term "tactile sensing" is mainly used among persons who are engaged in research for robots. The term "tactile sensing" is indicative of a force required to pick up an object. In other words, "tactile sensing" is used as the concept of a grip force. When a robot picks up an object with an excessively large grip force, the object may be damaged. On the other hand, when the grip force of the robot is very slight, the robot may drop the object, thereby causing the object to be damaged. Thus, it is very important to appropriately determine and control a desired grip force where desired operations are carried out using robots.
Meanwhile, the term "texture" is mainly used among persons (Kawabata, Japanese, and et al) who are engaged in research for clothing fabric. They use "texture" by defining this term by the term "hand value". Hand values are determined, based on the touch of fabrics derived from their physical properties such as tensile properties, bending properties, surface properties (surface roughness and frictional characteristics), shear properties, compressive properties, weight, and thickness. The hand value of a cloth is indicative of how much the cloth is appropriate for garments.
In this concept, however, visual texture is excluded. Warmth characteristics, namely, heat transfer characteristics, are also excluded. Moreover, fabrics are determined, based on only their appropriateness for garments, without taking into consideration the feeling and sensibility of human beings.
As an example of results of research associated with the reproduction of "texture", there is a texture display proposed by R. D. Howe and et al (R. D. Howe, W. J. Peine, D. A. Kontarinis and K. S. Son, "Remote Palpation Technology for Surgical Applications", The IEEE Engineering in Medicine and Biology Magazine, 14(3), pp. 318-323, May/June 1995). The texture display proposed by R. D. Howe includes a pin array consisting of 6.times.4 pins having a distance between pin centers corresponding to 2 mm. In this texture display, a desired shape is reproduced by adjusting the height of each pin. The height adjustment for each pin is carried out by a lever type height adjusting device mounted to each pin. The lever type height adjusting device includes a lever connected to the lower end of an associated pin, a shape memory alloy wire, and a spring.
However, such a texture display is adapted to provide tactile sensing information about the surface of an affected part of a patient, which is obtained by a probe inserted into the human body of the patient, to a surgeon. Furthermore, there is a limitation in reproducing fine texture due to an inferior spatial resolution corresponding to 2 mm.
As another example of results of research associated with the reproduction of "texture", there is a texture display proposed by Y. Ikei and et al (Y. Ikei, K. Wakamatsu and S. Fukuda, "Vibratory Tactile display of Image-Based Texture", IEEE Computer Graphics and Applications, pp. 53-61, November/December 1997). Similar to the above mentioned texture display, this texture display uses a pin array. This pin array consists of 10.times.5 pins having a distance between pin centers corresponding to 2 mm. In this texture display, a photographic image of an object to be displayed is first obtained and then subjected to a shading process, thereby determining the brightness at portions thereof respectively corresponding to the pins. Based on the determined brightness, each pin is adjusted in its vibration amplitude. Thus, a surface profile of the object is reproduced. In this case, vibrations are applied to each pin by a piezoelectric actuator. The vibration frequency of the piezoelectric actuator is fixed to 250 Hz.
However, this texture display also has a limitation in reproducing the texture of a fine surface due to an inferior spatial resolution thereof. To this end, it is necessary to develop a new texture display with a high spatial resolution enabling a texture reproduction other than a profile reproduction.